The two national security officials said 14 people were killed and 22 others injured, nine critically, when the drone struck the convoy Thursday near Radda in Yemen's al-Baitha province.

"This was a tragic mistake and comes at a very critical time. None of the killed was a wanted suspect by the Yemeni government," one official said.

The officials said the drones targeted four vehicles in the 11-vehicle convoy. Two vehicles were destroyed.

Among the killed were two prominent provincial tribal leaders, witnesses said.

CNN said U.S. officials declined to comment.

"All those who were killed were supportive of the government's anti-terror campaign," said Abdullah al-Kabra who saw the drone strike. "That will surely not be the case of their tribes and families if the government does not strongly intervene."

The drone operation in Yemen is part of a joint U.S.-Yemeni campaign against al-Qaida. Yemeni President Abdu Rabu Mansour Hadi has pledged to keep attacking terror elements until they surrender.

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